Embodiments of the disclosure relate generally to improved electric drive systems used in apparatuses such as electric vehicles.
Vehicles are mobile machines that are designed and used for transporting passengers and/or cargos from one place to another. Examples of the vehicles may include bicycles, cars, trucks, locomotives, tractors, buses, boats, and aircrafts. Traditionally, at least some of these vehicles are powered by engines such as internal combustion engines. The internal combustion engines may operate by burning fuels such as diesels, gasoline, and natural gas for providing necessary power so as to drive motion of the vehicles. However, with rising concerns of scarcity, cost, and negative environmental impact in association with the use of the diesels, gasoline, and natural gas, growing interests have been raised to develop electric powered vehicles such as fully/pure electric vehicles, hybrid electric vehicles (e.g., integration of a battery and internal combustion engine), and plug-in hybrid electric vehicles.
At least some of the electric powered vehicles are provided with two sets of electric motors. One is traction electric motor which is used to provide traction power for driving movement of the vehicle. The other is auxiliary electric motor which is used to provide drive power for performing various tasks such as lifting cargoes, plowing ground, and dumping materials. Typically, the traction electric motor is powered by a first converter (e.g., an inverter), and the output electrical power of the first converter is regulated by a traction motor controller. The auxiliary electric motor is powered by a second converter (e.g., an inverter), and the output electrical power of the second converter is regulated by an auxiliary motor controller which is independent from the traction motor controller. Due to this separate controller configurations, the first converter and the traction motor controller should be designed to provide desired output electrical power such that the traction motor can be operated to provide maximum output traction power for driving movement of the vehicle. Similarly, the second converter and the auxiliary motor controller should be designed to provide desired output electrical power such that the auxiliary motor can provide maximum output torque for performing certain tasks. However, in normal operations of the electric vehicles, the traction electric motor and the auxiliary electric motor typically are not operated to provide their maximum output electric power simultaneously. Thus, in most cases, the full capability of the electric drive system consisting of the first converter, the traction motor controller, the second converter, and the auxiliary motor controller is not sufficiently explored.
Therefore, it is desirable to provide electric vehicles with improved electric drive system.